Protective device for a controlling system of a sewage pump

ABSTRACT

A protective device for a controlling system of a sewage pump has a protective unit to protect a start capacitor and to avoid the start capacitor from burnout when an overload is occurred by actuating power source or when a transient voltage is occurred by malfunction of a controlling circuit after actuating the sewage pump. Therefore, the start capacitor is certainly protected and significantly improved in lifespan. The characteristic of this invention is that the protective device comprises an analogic or digital electronic circuit with a cutter efficiency.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a protective device for a controlling system of a sewage pump, and more particularly to an electronic-type protective device that controls pump operation and has a protective unit protecting a start capacitor in the controlling system to avoid the start capacitor from burnout.

2. Description of Related Art

As shown in FIGS. 3 and 4, a conventional sewage pump system in accordance with the prior art has an operational controlling circuit system 2 for controlling the operation of a sewage pump 1. The operational controlling circuit system 2 has a start capacitor 21 connected with a run capacitor 22 in parallel connection and with a switch 3 in series connection and further connected with an actuating coil and an operating coil on the sewage pump 1 to perform a combined circuit. In the operational controlling circuit system 2, the actuating coil 11 and the operating coil 12 drive the sewage pump 1 to function when the electrical power is supplied. Meanwhile, the switch 3 mounted on a shaft 4 of the sewage pump 1 has its contact changed from a normal closed (N.C.) status to a normal open (N.O.) status by a centrifugal force of the rotation of the shaft 4. Thereby, the start capacitor 21 is disconnected with the power supply to stop discharging so that the start capacitor 21 is protected from burnout and breakdown caused by the discharging or charging operation for a long period. However, the switch 3 is always kept being switched between the NO and NC status and its contact has carbon-deposition or oxidation incurred by electric sparkles of large current. Thus, the contact can not successfully disengage and is kept at the normal closed (N.C.) status that makes the start capacitor 21 to electrically connect the power source. When the start capacitor 21 is kept in discharging status, it will burnout sooner or later and then actuating coil 11 and the operating coil 12 will burnout as well.

According to above description, the conventional sewage pump system still has some drawbacks in use.

SUMMARY OF THE INVENTION

A main objective of the present invention is to provide a protective device for a controlling system of a sewage pump, wherein the protective device protects a start capacitor from keeping discharge and burnout when a switch is abnormally suspended.

To achieve the foregoing objective, the protective device for a controlling system of a sewage pump with a start capacitor and a run capacitor, the protective device comprising a protective unit having an analogic or digital electronic circuit with a cutter function to provide a protective efficiency to avoid the start capacitor in the sewage pump from burnout.

By having the protective unit, the start capacitor is protected from burnout and thus has an extended lifespan.

Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a sewage pump system with a protective device in accordance with the present invention;

FIG. 2 is a schematic circuit diagram for the sewage pump system with the protective device in the present invention;

FIG. 3 is a cross-sectional view of a conventional sewage pump system in accordance with the prior art; and

FIG. 4 is a schematic circuit diagram for the sewage pump system in accordance with the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A protective device for a controlling system of a sewage pump in accordance with the present invention has a protective unit to protect a start capacitor and to avoid the start capacitor from burnout when an overload is occurred by actuating power source or when a transient voltage is occurred by malfunction of a controlling circuit after actuating the sewage pump. Therefore, the start capacitor is certainly protected and significantly improved in lifespan. The characteristic of this invention is that the protective device comprises an analogic or digital electronic circuit with a cutter function.

The protective device for a controlling system of a sewage pump is applied to an operation-controlling circuit system 6 to drive a sewage pump 5 as shown in FIG. 1, wherein the operation-controlling circuit system 6 as shown in FIG. 2 has a start capacitor 61 and a run capacitor 62. The start capacitor 61 has one end connecting to a first output terminal 3 on a protective unit 7 and another end connecting with a second output terminal 4 on the protective unit 7 to further connect with an actuating coil 51 and an operating coil 52 of a sewage pump 5 to perform a closed circuit. The run capacitor 62 has one end connected to between the start capacitor 61 and the actuating capacitor 51 and another end diverging to connect with a third output terminal 2 on the protective unit 7 and the operating coil 52 that further extends to power source AC to perform a closed circuit. Additionally, a fourth output terminal 1 of the protective unit 1 also connects with the power source AC. The protective unit 7 is made of an analogic or digital electronic circuit with a function as cutter to protect the start capacitor 61 to avoid the start capacitor 61 from burnout when an overload is occurred by actuating power source AC (ON status) or when a transient voltage is occurred by malfunction of a controlling circuit after actuating the sewage pump 5. Therefore, the start capacitor 61 is certainly protected to keep on operation and significantly improved in lifespan. The protective unit 7 interiorly comprises an analogic or digital electronic circuit with a cutter function and has four terminals including a first terminal 1 served as a signal input end of power source AC, a second terminal 2 (the third output terminal as described above) kept at NC status with the first terminal 1 to control the start capacitor 61 and the run capacitor 62 to function the operating coil 52, a third terminal 3 (the first output terminal as described above) controlling the start capacitor 61 to function the actuating coil 51, and a fourth terminal 4 (the second output terminal as described above) kept at NO status with the third terminal 3 to control the start capacitor 61, the run capacitor 62 to function the actuating coil 51 and the operating coil 52. When the power source AC is supplied, the terminal 1 of the protective unit 7 receive the power energy to actuate the circuit system. Meanwhile, the terminal 1, terminal 2, terminal 3 and terminal 4 are connected to each other at NC status to make the start capacitor 61 to be electrified to function the actuating coil 51 and to make the run capacitor 62 to be electrified to function the operating coil 52. After the operation delays some time, the terminals 3 and 4 of the protective unit 7 switch from the NC status to the NO status to make the start capacitor 61 disconnected and stopped so that the start capacitor 61 is protected from burnout or breakdown caused by long-period operation of charge or discharge.

According to above description, the protective device for a controlling system of a sewage pump has the following advantage that:

The electronic-type protective unit has the cutter function that makes the terminals 3 and 4 to switch from the NC status to the NO status to isolate the start capacitor from power source and keep the start capacitor from charging and discharging operations. Thereby, the start capacitor is protected from burnout and breakdown during long-period operation.

Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present invention of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts any be resorted to without departing from the spirit and scope of the invention. 

1. A protective device for a controlling system of a sewage pump with a start capacitor and a run capacitor, the protective device comprising a protective unit having an analogic or digital electronic circuit with a cutter function providing a protective efficiency to avoid the start capacitor in the sewage pump from burnout.
 2. The protective device as claimed in claim 1, wherein the protective unit further comprises: a first terminal served as a signal input end of a power source; a second terminal kept at NC status with the first terminal to control the start capacitor and the run capacitor; a third terminal controlling the start capacitor; and a fourth terminal kept at NO status with the third terminal to control the start capacitor and the run capacitor. 